BioSensor Technologies, AIT-Austrian Institute of Technology, Muthgasse 11, 1190 Vienna, Austria.
Analyst. 2017 Aug 7;142(16):2995-3001. doi: 10.1039/c7an00970d.
Surface plasmon field-enhanced fluorescence is reported for the readout of a heterogeneous assay that utilizes low affinity split aptamer ligands. Weak affinity ligands that reversibly interact with target analytes hold potential for facile implementation in continuous monitoring biosensor systems. This functionality is not possible without the regeneration of more commonly used assays relying on high affinity ligands and end-point measurement. In fluorescence-based sensors, the use of low affinity ligands allows avoiding this step but it imposes a challenge associated with the weak optical response to the specific capture of the target analyte which is also often masked by a strong background. The coupling of fluorophore labels with a confined field of surface plasmons is reported for strong amplification of the fluorescence signal emitted from the sensor surface and its efficient discrimination from the background. This optical scheme is demonstrated for time-resolved analysis of chosen model analytes - adenoside and adenosine triphosphate - with a split aptamer that exhibits an equilibrium affinity binding constant between 0.73 and 1.35 mM. The developed biosensor enables rapid and specific discrimination of target analyte concentration changes from low μM to mM in buffer as well as in 10% serum.
表面等离激元场增强荧光用于读取利用低亲和力分裂适体配体的异质分析物。与目标分析物可逆相互作用的弱亲和力配体有可能在连续监测生物传感器系统中实现简便。如果没有更常用的基于高亲和力配体和终点测量的分析物的再生，这种功能是不可能实现的。在荧光传感器中，使用低亲和力配体可以避免这一步骤，但它带来了一个挑战，即与目标分析物的特异性捕获相关的弱光学响应，而背景也常常掩盖了这种响应。据报道，将荧光团标记与表面等离激元的受限场结合在一起，可以对从传感器表面发射的荧光信号进行强烈放大，并有效地将其与背景区分开来。该光学方案已成功应用于对所选模型分析物——腺苷和三磷酸腺苷的时间分辨分析，所采用的分裂适体的平衡亲和力结合常数在 0.73 至 1.35mM 之间。所开发的生物传感器能够快速、特异地分辨缓冲液中和 10%血清中低至 μM 至 mM 浓度变化的目标分析物。
